Machine for grinding drills



June 5, 1951 v F, DIXQN 2,556,073

MACHINE FOR GRINDING mums --Filed July 2, 194a 4 Sheets-Shee t 1 June 5, 1951 DlXON 2,556,073

/ MACHINE FOR GRINDING DRILLS I Filed July 2, 1948 4 Sheets-Sheet 2 22 20 Q1 Vl'Il/IIIIA wi W June 5, 1951 F. DIXON 2,556,073

MACHINE FOR GRINDING DRILLS Filed July 2, 1948 4 Sheets-Sheet 5 Patented June 5, 1951 UNITED STATES PATENT OFFICE 13 Claims.

My invention relates to a machine for grinding drills.

An important object of the invention is to provide a machine of the above-mentioned character which will grind the lips of the drill uniformly, and in a manner to provide proper lip clearance.

A further object of the invention is to provide a drill-grinding machine which swings the drill through a compound angle, in feeding the same against the face of the grinding wheel, so that the trailing edges or heels of the drill lips are ground deeper than the forward or cutting edges of the lips, while the point of the drill is simultaneously swung away from the grinding wheel, so that the wheel will not nick the cutting edge of the next approaching lip.

A further object is to provide a drill-grinding machine wherein the geometrical relation of various parts of the machine is such that a theoretically accurate or ideal point may be ground upon drills of standard sizes, and wherein the proper adjustments are provided for the accurate grinding of the different sizes of drills.

A further object is to provide means for accurately indexing the drill while grinding the same, so that the different lips of the drill may be brought into proper engagement with the grinding Wheel.

A further object is to provide a machine of the above-mentioned character which is simplified and which may be readily used by an unskilled operator.

A further object is to provide gauge means for determining the proper longitudinal adjustment of the drill, with respect to the grinding wheel, to prevent the grinding of too much material from the drill, or burning or destroying its temper.

A further object is to provide gauge means for maintaining the point of the drill concentric with the pivotal axis of the angularly adjustable holder, so that the drill point will remain in contact with the grinding wheel as the angle of the drill point is varied, regardless of the size of the drill.

A further object is to provide means for holding the drill point at the vertical center of the grinding wheel at the start of the grinding operation.

A still further object of the invention is to pro-. vide means for shifting the drill laterally across the face of the grinding wheel, to prevent scoring the wheel or forming a groove in the same.

Other objects and advantages of the invention will be apparent during the course of the follow ing description.

In the accompanying drawings, forming a part of this application, and in which like numerals are employed to designate like parts throughout the same,

Figure 1 is a perspective View of the machine, with the swingable drill-feeding assembly in the horizontal position,

Figure 2 is a plan view of the machine as shown in Figure 1,

Figure 3 is an end elevation of the machine,

Figure 4 is a fragmentary vertical section taken on line 44 of Figure 2,

Figure 5 is a front elevation of the machine,

Figure 6 is an end elevation of a bracket and associated elements, parts omitted,

Figure '7 is a vertical section taken on line l-T of Figure 6, part in elevation,

Figure 8 is a vertical section taken on line 88 of Figure '7,

Figure 9 is a horizontal section taken on line 9-.-9 of Figure 5,

Figure 10 is a vertical section taken on line Ill-4 E3 of Figure 9, parts omitted,

Figure 11 is a fragmentary vetrical section taken on line |-I l of Figure 9,

Figure 12 is a fragmentary horizontal section taken on line |2-l 2 of Figure 5,

Figure 13 is a fragmentary vertical section taken on line |3--|3 of Figure 2,

Figure 14 is a vertical sectional detail showing a gauge and associated elements,

Figure 15 is an enlarged fragmentary diagrammatic view showing the relation between the point of a drill and the inclined face of the gauge in Figure 14,

Figure 16 is a vertical section taken on line l6.l 6 of Figure 12, parts omitted,

Figure 17 is an enlarged fragmentary diagrammatic plan view of a drill and grinding wheel, wherein the leading or cutting edge of one of the drill lips is being dressed or ground,

Figure 18 is a similar view illustrating the relation of the drill to the grinding wheel when the swingable drill-feeding assembly is in an intermediate position,

Figure 19 is a similar view showing the relation between the drill and grinding wheel when the swingable assembly is at the bottom of its travel and the heel or trailing edges of the drill lip is being ground,

Figure 20 is a fragmentary perspective view illustrating the holding of a drill having a tapered shank.

In the drawings, where for the purpose of illustration is shown a preferred embodiment of my invention, the numeral l5 designates a table, upon which is rigidly mounted a vertical bracket it, having a horizontal bore IT for receiving a cylindrical shank [8, having a longitudinal groove l9, to receive a key 25. The shank 18 has a reduced screw-threaded extension 2|, receiving a nut 22. Formed integral with the shank i8 is a vertical post 22', provided at its lower end with the split head 23, forming jaws 24, drawn together by a bolt 25.

The machine comprises a bed 25, including a cylindrical rod 21 which is horizontally disposed and clamped between the jaws 24. Rigidly mounted upon the rod 2'! are bars or ends 28, having cylindrical openings 29, for receiving the reduced cylindrical ends 30 of guide rods 31 which are square in cross section, forming upper and lower V-shaped portions, Figure 10. The ends 30 have annular grooves 52, for receiving the ends of set screws 33, whereby the guide rods 3| are locked to the ends 28. The ends 28 are provided between the guide rods 3! with vertical screwthreaded openings 34, for receiving the screwthreaded ends of vertically adjustable legs 35, having feet 36, to engage upon the table l5. The legs 35 carry lock nuts 31. It is thus seen that the legs 35 may be adjusted to level the bed 26, and engage upon the table, whereby the bed will be securely supported in the adjusted position by the legs and by the bracket i 6.

Longitudinally adjustably mounted upon the guide rods 3! is a carriage 31', the lower face of which has V-shaped grooves 38, Figures 1 and 10, to receive the upper corners of the guide rods 3!, and a lower plate 39 is provided having V-shaped grooves 40 to receive the lower corners of the guide rods 3! therein. The carriage 3'! is provided near its ends with vertical openings M, which receive adjusting bolts 42, the lower screwthreaded ends of which engage in screw-threaded openings 43 in the lower plate 35. These bolts #12 serve to draw the carriage 31 and plate 39 together until the carriage has an accurate sliding engagement with the guide rods 3!. The bolts 42 have annular grooves 45, to receive the inner ends of set screws 45, engaging in screwthreaded openings 45. The carriage 51 is shifted longitudinally by means of a link 48, pivoted to the carriage by one of the bolts 42, and this link 48 is pivotally connected with a lever 49, at 5:3. The lever 49 is pivotally connected with the adjacent end or bar 28 by a bolt 5i.

Extending transversely of the carriage 57' is a slide 52, operating in a dovetailed groove 54 formed in the carriage, Figure 11. A shim 55 is mounted in the groove 5d and is engaged by adjustable set screws 56 to compensate for wear. The slide 52 is provided upon its top surface, and at one longitudinal edge with a micrometer scale 51, for coaction with a scribe line 58, formed upon the carriage 3'1, Figure 9. An adjusting screw 59 is arranged beneath the slide 52 and has a swiveled connection with a depending portion 50, and is provided at its outer end with a knurled knob 6|, disposed outwardly of the slide 52 to turn the feed screw 55. The feed screw engages in a transverse screw-threaded opening 62 in the carriage 31'.

Arranged above the slide 52 at its inner end is an L-shaped bracket 59 which is horizontally angularly adjustable, and includes vertical and horizontal arms 65' and 6E". The horizontal arm 6|: has an opening 62', Figure 6, for pivotally recelving a vertical pin 63 rigidly mounted upon the inner end of the slide 52. This pin 63 has an l 4 per screw-threaded portion 64, receiving a nut 65, and a square head 55' disposed in a square recess 66' formed in the bottom of the slide 52. By manipulation of the nut 55 the bracket 59 can be angularly adjusted and locked in the selected adjusted position. The arm 6! is provided with a circularly curved head 66, integral therewith, and this head is provided with a scale 61, graduated in minutes, for coaction with a scribe line I 68 formed upon the top surface of the slide 52 for indicating the angular adjustment of the bracket 59. The innermost end of the slide 52 is enlarged, forming lateral shoulders L, which limit the outward longitudinal travel of the slide 52, Figure 9.

Formed integral with the upper end of the vertical arm 50 is a tubular bearing head 59, Figure 7, receiving ball bearings 16, having a pressfi't therein. These ball bearings '10 are sealed at their outer ends, and their inner ends are spaced apart, providing a passage ii to receive lubrication from an Alemite fitting f2. Held within the inner races of the ball bearings ll! is a horizontal cylindrical shaft 13, provided at its inner ends with a cylindrical eccentric or crank 14, integral therewith. The crank '54 is in the lowermost position when the vertically swingable drillfeeding assembly 174, to be described, is in its top horizontal position.

The numerall5 designates a bracket included within the vertically swingable assembly '14. This bracket 15 includes arms 76 and TI, arranged at an obtuse angle. The arm 15 has an opening 21, to receive the eccentric 14, Figure 6. The arm 76 is split and clamped to the eccentric 14 by a bolt 18. When the bracket 15 is at the top horizontal position, the eccentric is at the bottom of its travel, or depending from the shaft 13. Adjustable stop means are provided to limit the upward movement of the assembly hi, including an inner ring I9 permanently clamped to the shaft 13, and. an outer ring Bil mounted to turn upon the inner ring. The outer ring carries a set screw 8i, the point of which engages within an annular groove 82 formed in the inner ring lit. The oute ring may therefore be turned with respect to the shaft 13 and locked thereto in the selected adjusted position. The outer ring 85 is provided with a radial stop lug 83 to engage a stop lug 86 rigidly secured to the bearing head 59. The vertical arm 65 has a block 85 rigidly secured thereto, carrying an adjustable-screw-stop 86, to limit the downward swinging movement of the bracket by contacting the underside of the arm 16, Figure 6. The screw-stop has a knurled head 87 and carries a knurled lock nut 58.

The numeral 89 designates a bar or carriage, parallel to the arm Ti, and spaced laterally therefrom and having a feed screw rigidly secured thereto. This feed screw preferably has square threads. The feed screw 95 is slidably mounted in an opening 9i formed in the arm TI, and car ries a knurled adjusting nut Q2, arranged between the head 93 and the arm ii, and the head. 53 is rigidl secured to the arm H by means of a rod 54. The numeral 95 designates a head formed integral with a tube 95, extending through an opening 9i the carriage 39 and clamped therein by a set screw'fil. The tube 93 extends. slidably through an opening 98 formed in the arm "fl, and this arrangement prevents rotation of the carriage 29 about the feed scre Rigidly secured to the carriage 89, and held within a dovetailed groove formed in the arm H is a scale 99 graduated in 32nds of an inch, and cois parallel to the arm TI.

acting with a scribe line I09 formed upon the arm Ill. The scale 89 is provided, so that the head 95 can be adjusted radially of the eccentric M in connection with drills of different standard diameters.

The head 95 is part of the drill support and is provided with a V-shap-ed groove IIlI to receive the drill Hi2. The head 55 also has a slot I03 for receiving a fiat rectangular plate I04 of an indexing dog I95, having a point I06 to engage Within the spiral grooves or flutes of the drill. The plate has a tail It? extending through the tube IE6, and projecting outwardly beyond the same, so that the indexing dog may be longitudinally adjusted; and the indexing dog Ifi5 is clamped in the selected adjusted position by a set screw Hi8, engaging in the head 95 and having a knurled head. When the drill IE2 is positioned within the V-shaped groove IIII of the head, and is held against turning movement by the point H16 engaging within a flute of the drill, the drill may be lifted turned 180 degrees, and the point I 86 of the dog will again enter the spiral flute of the drill and hold it against further turning movement. This action presents the faces or lips of the drill in succession for grinding action. A rod I89 is rigidly secured to the head 85, and This rod has a second head IIt longitudinally adjustably mounted thereon, carrying a set screw III, the point of which engages within a longitudinal groove II2 formed in the rod IQI]. The head III) has an opening H3 formed therein, having a V-shaped bottom He. The apex of this V-shaped bottom IN is spaced the same lateral distance from the rod Ills that the apex of the groove I9! is spaced therefrom, Figure 12. The head H5 is provided at its top with an adjusting screw H5 to clamp the drill m2 in the opening I I3, and this adjust ing screw has a knurled head, as shown. The outer end of the opening II 3 may be covered by a plate or end I I6, having an opening to slidably receive the rod I89. This plate IE6 has a notch II? to receive a set screw II 8, tapped into the head III}. This set screw is employed to clamp the plate IIB to the head Ill]. The plate H6 is further equipped with a set screw IIQ, having a knurled head, for clamping engagement with the rod I89. When the drill It? has a cylindrical shank, the plate H6 is locked to the head H0, and the head is moved toward the free end of the rod I 39 for a suitable distance, and the cylindrical of the drill is inserted in the open ing I I3 and the set crew i I5 is turned to clamp the drill in the head 5 Ill. The head I it is now moved toward the head t5, and in order that the correct longitudinal adjustment of the drill may be efiected, a swingahle gauge I253 is moved into a position in alignment with the longitudinal axis of the drill. gauge I26 is carried by an arm I2I, pivotally mounted upon the carriage 89, at I22. The IiZI has a shoulder I23 which limits the downward swinging movement of the arm. The generally vertical face 52A! of the gauge I23 is inclined slightly when the gauge is in the lowered position, Figures 14 and 15, and when the point of he drill Hi2 contacts with the inclined face and when the gauge is swung upwardly from such point, the point will clear the inclined face during this swinging action so that the face will. not be scratched nor the drill point injured. When the drill has a tapered shank the plate lie is separated from the head III Figure 20, so that the end of the tapered 6 I shank contacts the plate and the cylindrical portion of the drill engages in the bottom H4. The plate H6 is clamped to the rod Hi9 after the head has been moved forwardly so that the point of the drill will contact the gauge I26.

The post 22 is provided at its top with a bearing head I25, receiving ball bearings I26, identical to the ball bearings I0 and having the same lubrication arrangement, as shown. These ball bearings receive a horizontal shaft I21, driven by a grooved pulley I28, receiving rotation from any suitable source. A rotary grinder I29 formed of Carborundum, or any other suitable material, is mounted upon the free end of the shaft I27! in the usual manner.

A generally forwardly extending handle I353 is provided to facilitate swinging the drill-feedassembly I4. At its inner end, the handle I30 carries a depending shank Isl, having a lower reduced screw-threaded extenion I32, engaging in a screw-threaded opening in the top of the arm II. The extension I32 serves the dual purpose of securing the handle I 36 to the assembly I I and serving as a set screw to engage upon the screw as for locking the carriage 89 in the selected adjusted position, Figure 13.

The shaft I2] is horizontal and parallel to the longitudinal axis of the carriage 3'1. The cen tral longitudinal axis of the shaft I Z'I and the central longitudinal axes of the eccentric I4 and drill I02 are all horizontal and in the same horizontal plane, when the drill-feeding assembly 14' is in the raised position. Since the drill I02 and rod I09 are parallel to the arm I1, and the arm I6 is at right angles to the longitudinal axis of the shaft'IB, the drill I02 and carriage 89 are at a slight angle to the longitudinal axis of the shaft l3, such as'approximately 10 degrees but this angle may be varied slightly.

It is to be noted that the geometry of this machine is such that when the assembly 14 is in its upper horizontal position and the drill I02 is properly adjusted, as previously described, the center of the drill point will be disposed directly over the vertical axis of the pin 63, and the point of the drill will. be at the same elevation above the bed 26 as the longitudinal axis of the grinding Wheel I29. The drill will engage the grinding Wheel at the vertical center of the same. The projected longitudinal axes of the drill and eccentric 'I I will intersect directly over the axis of the pin 63, at this time.

The operation of the machine is as follows:

The bracket 59" is angularly, adjusted for setting the desired angle to be ground upon the point of the drill, and the carriage 89 is adjusted laterally corresponding to the diameter of the drill being ground. The drill is longitudinally adjusted by the use of the gauge IZII and by moving the head III) longitudinally, as stated. When this has been done the tip of the drill point will be directly over the axis of the pin 63. When the drill-feeding assembly I4 is swung to the top of its travel, and is disposed horizontally, the slide 52 is then adjusted for bringing the point of the drill into contact with the periphery of the grinder I28, which contact is indicated by sparks. The extent of grinding may be varied by the use of the knob GI in conjunction with the scale 51 on the slide 52. However, the normal feeding of the drill point into the grinding wheel is accomplished by swinging the assembly I4 vertically. With the assembly I I arranged horizontally, or in its uppermost position, with the lugs 83 and 84 arranged as shown in Figure 8, the grinder I29 first grinds the leading or cutting edge I33 of a drill lip I34, and when the assembly I4 is swung downwardly the eccentric 74 causes the drill point to swing laterally toward the periphery of the grinder I29. The lip I 34 being ground, as it moves downwardly, is thus shifted slightly toward the periphery of the grinder and this continuous slight feeding action results in the lip of the drill being ground slightly inclined or deeper toward its trailing edge or heel I35, and the leading cutting edge I33 of the drill lip I34 is disposed above or in advance of the trailing edge or heel I35 when the grinding action is completed by the full downward swing of the assembly I4. This abovedescribed grinding action is very important for the proper use of a drill. While the assembl 13 is swinging downwardly, due to the slight angular relation of the longitudinal axis of the drill to the longitudinal axis of the shaft I3, the point I36 of the drill is swung slightly away from the periphery of the rotary grinder I29. This feature is very important because it prevent the cutting edge of the next approaching lip of the drill from being nicked by the grinding wheel adjacent to the point I36. There is therefore a compound movement imparted to the drill I32 while the assembly i l swings downwardly, one component.

of which causes the grinder I29 to progressively cut the lip I33 deeper toward the trailing edge or heel I35, and the other component moves the drill point I36 away from the grinder I29, as stated, see Figures 17, 18 and 19.

After one lip I34 has been ground, the drill is lifted and turned 180 degrees upon its longitudinal axis in the head III] and the next lip I34 will be ground to the identical extent and in the identical manner as the preceding lip I34, by again swinging the assembly I4 from its upper horizontal position downwardly until the arm I6 contacts the screw-stop 86. None of the previously described adjustments are changed When support for carrying a rotary grinder, an angu-- larly adjustable supporting member mounted upon the support and having a turning point, a

' second member arranged near the rotary grinder,

means to pivotally mount the second member upon the angularly adjustable supporting member including a pivot element provided with an eccentric extension having a central longitudinal axis, a drill holding device mounted upon the second member and having holding means for receiving the drill, the holding means having a longitudinal axis extending generally longitudinally of the central longitudinal axis of the eccentric extension and arranged at a slight angle from the parallel with relation to such axis, the arrangement being such that the projected longitudinal axis of the drill and the projected central longitudinal axis of the eccentric extension will intersect at a point in alignment with the turning point of the angularly adjustable member when thesecond member is shifted to a position for starting the grinding operation.

- support, means mounted upon the support for carrying a rotary grinder, a swinging supporting device mounted upon the support, a carriage mounted upon the supporting device, an adjusting screw secured to the carriage and engaging the supporting device, a feed nut engaging the screw, a tube secured to the carriage and slidably engaging the supporting device, a head carried 'by the tube and having a recess to receive a drill,

an index element arranged within the tube 'to engage with the drill, adjustable means carried by the head to clamp the index element in the selected position, a rod secured to the head and extending axially of the drill, and a drill holding device adjustably mounted upon the rod.

3. A machine for grinding drills comprising a support, means mounted upon the support for carrying a rotary grinder, a swinging supporting device mounted. upon the support, a carriage mounted upon the swinging supporting device, a head mounted upon the carriage and having a recess to receive the drill, a rod mounted upon the head and extending axially of the drill held within the recess, a head longitudinally adjustably mounted upon the rod and having an opening toreceive the drill, a plate separate from the second head and arranged upon that side of the second head remote from the first head, a set screw for clamping the plate to the second head, and a separate set screw for clamping the plate for clamping the drill in place therein.

l. A machine for grinding drills comprising a support, means mounted upon the support for carrying a rotary grinder, a swinging supporting device mounted upon the support near the rotary grinder, a carriage mounted upon the swinging supporting device, a head mounted upon the carriage and'having a recess to receive the drill, screw means to adjust the carriage with respect to the supporting device, a scale to indicate the adjustment of the carriage in accordance with different diameter size drills, a set screw carried by the supporting device for clamping engagement with the screw means, a handle to swing the supporting device and carried by the set screw and rigidly connected with the set screw to turn it, a second handle secured to the head,

7 and a drill holding device mounted upon the second handle.

5. A machine for grinding drills, comprising a support, a substantially horizontal shaft mounted upon the support for carrying a rotary grinder,

a carriage mounted upon the support at an elevation beneath the substantially horizontal shaft to move longitudinally of and parallel with such shaft, a slide mounted upon the carriage to move transversely thereof at substantially a right angle to the shaft, an L-shaped bracket including a horizontal arm and a vertical arm, means to pivotally mount the horizontal arm upon the slide, the vertical arm being arranged near one end of the substantially horizontal shaft and upon one side of its longitudinal axis, a pivot element carried by the upper end of the vertical arm and horizontally disposed and having an eccentric extension, an L-shaped bracket which is substantially horizontal when in the raised position and including first and second arms, the first arm being clamped upon the eccentric extension, the end of the first arm and the eccentric extension being disposed upon the same side of the axis of the substantially horizontal shaft with the vertical arm of the first named L-shaped bracket, the second arm being disposed at an obtuse angle with relation to the first arm and extending upon the opposite side of the substantially horizontal shaft with relation to the occentric extension, a drill holding device mounted upon the free end portion of the second arm for holding a drill parallel with the second arm, the drill and eccentric extension being arranged in spaced end-to-end relation and disposed upon opposite sides of the substantially horizontal shaft and disposed at a slight angle from the parallel with respect to the eccentric extension, and a gauge mounted upon the drill holding d'evice to contact with the free end of the drill and adjustable so that its contact face is in alignment with the pivot means for the horizontal arm of the first named L-shaped bracket.

6. A machine for grinding drills, a support, a substantially horizontal tatablc shaft mounted upon the support for carrying a rotary grinder, a substantially horizontally angularly adjustable supporting member mounted upon the support and having a turning point, a substantially vertically swingi' g member arranged near the rotary grinder, a pivot element mounted upon the angularly adjustable supporting member and arranged substantially horizontal and having an axial eccentric extension which is secured to the substantially vertical swinging member, a drill holding device mounted upon the swinging member and having drill engaging parts ar-- ranged in end-to-end relation to the eccentric extension and slightly inclined with respect to the longitudinal axis of such ecoen 'ic extension, the drill holding device being arranged. to bring the lip of the drill into engagement with the periphery of the grinder, the shaft, the eccen trio extension and the drill engaging parts of the drill holdi g device being disposed in the same substantially horizontal plane when the swinging member is in the raised starting position, and the central longitudinal of the eccentric extension being in alignment with the turning point of the angularly adjustable supporting member when the swinging member is in the raised starting position.

7. In a machine for grinding drills, a support, a shaft mounted upon the support for carrying a rotary grinder, an angularly adjustable supporting member mounted upon the support and movable in a plane parallel with the longitudinal axis of the shaft, a swinging member arranged near the grinder and movable in a plane at right angles to the longitudinal axis of the shaft, a pivot element mounted upon the angularly adjustable supporting member and arranged in a plane parallel with the longitudinal axis of the shaft and having an axial eccentric extension which is secured to the swinging member to turn therewith, a drill holding device mounted upon the swinging member and having drill engaging parts arranged in end-to-end relation to the eccentric extension and slightly inclined with respect to the longitudinal axis of such eccentric extension, the shaft, eccentric extension and drill engaging parts of the drill holding device being disposed in the same plane when the swinging member is in the starting position, the central longitudinal axis of the eccentric extension being in alignment with the turning point of the angularly adjustable member when the swinging member is in the starting position, and means connected with the drill holding device and swinging member to shift the drill holding device radially with respect to the turning point of the angularly 10 adjustable member without disturbing the in clination of the drill engaging parts with re-- spect to the longitudinal axis of the eccentric extension.

8. In a machine for grinding drills, a support, a shaft mounted upon the support for carrying a rotary grinder, an angularly adjustable sup porting member mounted upon the support and movable in a plane parallel with the longitudinal axis of the shaft, a swinging member arranged near the grinder and movable in a plane at right angles to the longitudinal axis of the shaft, a pivot element mounted upon the angularlyadjustable supporting member and arranged in a plane parallel with the longitudinal axis of the shaft and having an axial eccentric extension which is secured to the swinging member to turn therewith, a drill holding device mounted upon the swinging member and having drill en gaging parts arranged in end-to-end relation to the eccentric extension and slightly inclined with respect to the longitudinal axis of such eocen-' trio extension, the shaft, eccentric extension and drill engaging parts of the drill holding device being disposed in the same plane when the swing ing member is in the starting position, the central longitudinal axis of the eccentric extension being in alignment with the turning point of the angularly adjustable member when the swinging member is in the starting position, and a gauge mounted upon the swinging member and having a face to contact with the point of the drill, the gauge being adjustable so that said face may be brought into the path of travel of the point of the drill and in alignment with the turning point of the angularly adjustable supporting member.

a A machine for grinding drills, comprising a support, a rotatable shaft mounted upon the support for a rotary grinder, a' bracket mounted upon the support, a member arranged near the rotary grinder, means to pivotally mount the'member upon the bracket including a pivoted element having a turning axis which, is inclined with respect to the rotatable shaft and provided withv an axial eccentric extension, a drill holding devicemou'nt'ecl upon the member in end-toeend relation with the eccentric extension and" axially spaced from the eccentric extension and having holding for receiving the drill, the holding means having drill engaging parts extending longitudinally of d turning axis and arranged at a slight angle with relation to the turning axis, said drill parts holding the drill so that its lon itudinal axis is at a slight angle with respect to said turning axis.

10. A machine for grinding drills, comprising a support, a rotatable shaft mounted upon the support for carrying a rotary grinder, an angularly adjustable supporting member mounted upon the support near the rotary grinder and having a turning point, a second member arranged near the rotary grinder, means to pivotally mount the second member upon the angularly adjustable supporting member including a pivot element having a turning axis and provided with an eccentric extension, turning axis being inclined with respect to the rotatable shaft, a drill holding device mounted upon the second member and including drill engaging parts arranged in end-tc-end relation with the eccentric extension axially spaced from the eccentric extension, the -l engaging parts being arranged at a slight angle with relation to the turning axis, the drill engaging parts holding a drill so that the longitudinal axis of the drill is arranged at a'slight angle with respect to the turning axis, and a gauge connected with the drill holding device for contacting with the end of the drill so that such end is brought in alignment with the turning point of the angularly adjustable supporting member at the starting of the grinding action.

11. A machine for grinding drills, comprising a support, a rotary grinder mounted upon the support and having an axis of rotation and a periphery, a supporting member mounted upon the support near the rotary grinder, a pivot element mounted upon the supporting member and having a turning axis inclined with relation to the axis of rotation of the grinder and provided with an axial eccentric extension, a drill holding device to bring the lip of the drill into contact with the periphery of the grinder, mounting means secured to the eccentric extension so that they move together and carrying the drill holding device so that the drill holding device will hold the drill with the longitudinal axis of the drill at a slight angle to the turning axis, the drill holding device and drill being arranged in end-to-end relation with relation to the turning axis and axially spaced from the turning axis.

12. A machine for grinding drills, comprising a support, a substantially horizontal rotatable shaft mounted upon the support, a substantially vercentric extension and inclined slightly with re; spect to the central longitudinal axis of the eccentric extension, the drill holding device being adjustable to hold the drill so that its point will be in alignment with the turning point of the angularly adjustable bracket.

13. A machine for grinding drills, comprising a support, a substantially horizontal rotatable shaft mounted upon the support, a substantially vertically rotating grinder mounted upon the shaft and having a periphery and end, an upstanding bracket disposed near the end of the grinder and including an elongated horizontal portion, a pivot element connecting the horizontal elongated portion with the support so that bracket may be angularly adjusted with respect to the axis of rotation of the grinder, a substantially vertically swinging member having ends, a substantially horizontal pivot element mounted upon the bracket and having a turning axis extending longitudinally of the elongated horizontal portion ti'cally rotating grinder mounted upon the shaft and having a periphery and end, a substantially horizontally angularly adjustable b r a c k e t mounted upon the support and having a turning point, a substantially vertically swinging member arranged near the rotary grinder, a substantially horizontal pivot element mounted upon the angularly adjustable bracket and having a turning axis extending radially of the turning point orthe angularly adjustable bracket and inclined with respect to the shaft and provided with an axial eccentric extension upon which the substantially vertically swinging member is mounted, the eccentric extension having a central longitudinal axis, a drill holding device mounted upon the swinging member and having drill engaging parts arranged in end-to-end relation to the eccentric extension and axially spaced from the ecand inclined with respect to the axis of rotation of the grinder and provided with an axial eccentric extension upon which one end of the substantially vertically swinging member is mounted, the eccentric extension having a central longitudinal axis, a drill holding device mounted upon the opposite end of the swinging member to be arranged adjacent to the periphery of the rotary grinder and having drill engaging parts spaced axially from the eccentric extension and inclined slightly with respect to the central longitudinal axis of the eccentric extension.

FATE DIXON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 327,758 Birkenhead Oct. 6, 1885 512,545 Gilman Jan. 9, 1894 1,388,039 Hinz Aug. 16, 1921 1,674,224 Rabut June 19, 1924 2,356,175 Olson et a1. Aug. 24, 1944 2,415,121 Wiken et a1 Feb. 4, 1947 

